Lubricant



PATENT OFFICE LUBRICANT Benjamin Gallsworthy, Glenham, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing.

14 Claims.

. This invention relates to lubricants and pertains more particularly to a-lubricating compound or composition which is suitable for gear lubrication, particularly where high pressures are encountered, and which is also useful in all types of machines wherein, due to severe conditions of temperature and wear, it is desirable to have incorporated in'the lubricant a component which will form an efiicient lubricating film and will not break down under hard service.

It is an object of the invention to produce a lubricant having incorporated therein a finely 1 divided solid constituent, such as lead sulfide,

and to provide a mixture having such consistency that the solid constituent may remain in suspension under normal'conditions but under severe service conditions may deposit, on the bearings and other moving parts with which it is in contact, a film that will reduce friction and prevent scoring and seizure.

The method of preparing my improved lubricant comprises reacting a lead soap with sulfur to precipitate finely divided lead sulfide therein and then dispersing the resultant mixture in a hydrocarbon oil. I have discovered that when a lead soap and sulfur are subjected to a sufficiently high temperature, the soap is decomposed by the sulfur and there is produced a precipitate consisting of very fine particles of lead sulfide. The sulfur will obviously precipitate a relatively large amount of leadsulfide due to the high molecular weight of the lead; however, I prefer to use only enough sulfur to precipitate a portion of the lead and to permit the remainder of the soap, which is also a good lubricant, to remain unreacted.

The lead soap used, according to the invention, may be prepared by, methods described in the literature and preferably by the so called dry method wherein litharge is reacted with a hot fatty oil or fatty acid. Lead soaps which have been found to be suitable comprise the lead soaps of animal oils, vegetable oils and naphthenic acids. I prefer, however, for economic reasons, to use lead oleate or the lead soaps of certain fish oils, such as menhaden oil.

The lead sulfide is precipitated in the soap by' heating the soap to suitable temperatures, say from 250 F. to 450 F. and preferably in the region of 300 F.-350 F., then adding the sulfur thereto and agitating the mixture for a sumcient time to insure the desired reaction. Usually about one-half hour to three hours is sufficient to produce complete reaction. It will be understood, however, that the above condi- Application February 18, 1932, Serial No. 593,880

tions are only by way of example and that the method may be varied according to the type of soap under preparation. In some cases it may be desirable first to mix the sulfur and soap together and then heat the mixture to the proper temperature, or it might be advantageous to add the sulfur to the hot oil in batches, or gradually add the'sulfur after the mixture is at a suitable temperature.

The amount of sulfur used to precipitate the lead sulfide will vary somewhat according to the type of lubricant under preparation. In general, however, it has been found that an amount of sulfur ranging from 0.25% to 5.0% of the weight of the soap is satisfactory for ordinary purposes and preferably about 1% of sulfur by weight. The corresponding quantity of lead sulfide would range from approximately 1.9% to 37.5% of the soap and 7.5% by weight inthe case of the preferred amount.

The soap and precipitated lead sulfide'are incorporated in the oil by any suitable means such as agitating the two in a tank or kettle. The materials are preferably mixed hot, although this is not always necessary, in order to lower the viscosity and hasten the mixing operation. A suitable temperature for the mixture may range from 100 F.-300 F., or the materials may be mixed at approximately the same temperature as that at which the soap is prepared or at which the lead sulfide is precipitated therein.

While an operation has been described in which a mixture of the soap and precipitated lead sulfide are first prepared and the mixture then incorporated in the oil, it will be understood that the invention is not limited to such a procedure.

Instead, the soap may be dissolved in the oil first and then lead sulfide precipitated by addition of sulfur to the oil-soap mixture to produce the lead sulfide in situ.

The kind of oil suitable for use as a solvent for the soap and in which to suspend the lead sulfide may vary within quite wide limits, for example, from a low viscosity oil, such as 70 viscosity stock at 100 F., to heavy residues such as those which have been used heretofore in gear compounds and car oils. It is preferred that the all be heavy enough to provide substantial lubricating qualities and also to have sufficient consistency that the lead sulfide will remain for considerable time in suspension. It will be observed that I may use any lubricating oil, but in the preparation of gear compounds I prefer to use a heavy oil, such as a crude residuum or blends thereof with various lighter lubricating oils.

lead sulfide in suspension, I add about 4%30% by weight of the mixture to the oil. This quantity corresponds to about 0.01% to 1.5% added sulfur or in the region of 0.1%-10.0% lead sulfide. In the preparation of high pressure gear lubricants for example, I prefer to use about 10%-20% of the prepared soap mixture in a crude residuum, or in other words, about 0.025% to 1.0% of added sulfur or about 0.2%'I .0% of lead sulfide.

My improved lubricant has the advantage that it contains a soap which enhances the lubricating property and particularly a finely divided solid constituent which will provide a lubricating film under extreme pressures and severe conditions of temperature and of wear. The lead sulfide is finely divided whereby a uniform and smooth deposition of the particles on the bearing may be obtained to produce a continuous lubricating film. The size of the lead sulfide particles in normal operations may range from 8-25 microns,

' although in some cases much smaller sizes may be obtained, such as approaching or having colloidal dimensions. 7

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims. 7

What I claim is:

1. The method of preparing lubricants which comprises reacting a lead soap with sulfur whereby finely divided lead sulfide is precipitated in the soap and then dispersingthe resulting mixture in a hydrocarbon oil.

'2. The method of preparing lubricants which comprises subjecting a lead soap and sulfur to a temperature sufiicient to precipitate finely divided lead sulfide in the soap and then mixing the resulting mixture of soap and lead sulfide with a lubricating oil.

3. The method'of preparing lubricants which comprises heating a lead soap to a temperature of 250 F.-450 F., adding suflicient sulfur thereto to react with a portion of the lead in the soap, maintaining said temperature for a sufiicient timeto cause substantial precipitation of lead sulfide in the soap' and then mixing the resultant mixture with a lubricating oil.

4. Themethod of preparing gear lubricants When adding a soap which already contains the which comprisessubjecting a lead soap and .0.25%-5% by weight of sulfur to a temperature of 250 F.-450 F., thereby precipitating a portion of the lead in the soap as finely divided lead sulfide and then incorporating the resultant mixture in a heavy hydrocarbon oil.

5. The method of dispersing finely divided lead sulfide in a lead soap which comprises subjecting a lead soap to a temperature of 250 F.-450 F. and while so heated adding 0.25%-5% by weight of sulfur thereto andagitating the mixture to cause precipitation of finely divided lead sulfide and to effect uniform dispersion thereof throughout the mass.

6. A composition of matter comprising a hydrocarbon oil, lead soap and finely divided lead' sulfide, the mixture having such consistency as to be suitable for lubricating purposes.

7. A lubricant comprising a lubricating oil, lead soap and 0.01 %-1.5% by weight of sulfur in the form of finely divided lead sulfide.

8. A gear lubricant, comprising a heavy hydrocarbon oil to which has been added about 10%- 20% by weight'of a lead-soap compound consisting of lead soap and 0.25 %-5% by weight of sulfur in the form of lead sulfide.

9. A composition of matter comprising lead soap and 0.25%-5% sulfur as lead sulfide dispersed therein, the lead sulfide having a particle size of 8-25 microns. I

10. A composition of matter having lubricating properties comprising a sulfurized mixture of a hydrocarbon lubricating oil and lead soap, said mixture containing a substantial amount of finely divided lead sulfide.

11. A lubricant comprisinga sulfurized mixture of a hydrocarbon oil having lubricating properties and lead oleate, said mixture containing a substantial amount of finely divided lead sulfide.

12. A lubricant comprising a sulfurized mixture of a hydrocarbon lubricating oil and lead naphthenate, said mixture containing a substantial amount of finely divided lead sulfide.

13. A composition of matter comprising a hydrocarbon oil-having lubricating properties, lead oleate and finely divided lead sulfide.

14. A composition of matter comprising a hydrocarbon oil having lubricating properties, lead naphthenate and finely divided lead sulfide. 7

BENJAMIN GALLSWOR'I'HY. 

